The invention relates to an improved hydraulic lock, and in particular to a push button control for a hydraulic lock.
In U.S. Pat. No. 5,005,677 to Bucholtz et al., there is disclosed a hydraulic lock that is ideally suited for use in adjustable back seats of the type typically found on aircraft, trains, buses, and the like. The lock includes a hydraulic cylinder that is mounted between the seat back and the stationary frame of the seat. The cylinder includes a piston rod that is connected to a piston housed within the cylinder. A valving system permits fluid in the cylinder to flow across the piston under controlled conditions thereby permitting the piston rod to be extended or retracted depending on the direction of force exerted on the seat back. A push button control is generally mounted upon the arm rest of the seat which, when depressed, opens the valving system.
As further disclosed in the above noted Bucholtz et al. patent, the push button is connected to a pin slidably contained in the piston rod of the hydraulic lock. To tilt the seat back out of a full upright position, the seat occupant first depresses the button which in turn moves the pin to an operative position unseating a poppet control valve and allowing fluid to flow around the piston. Applying a slight rearward force upon the back of a seat by the occupant causes the seat back to tilt. The exchange of fluid from one side of the piston to the other continues until the back is placed in a desired position whereupon the seat occupant releases the push button closing the poppet valve locking the back in the desired position. To return the back to a full upright position, the seat occupant again depresses the button and a forward force is applied to the back.
Push button control mechanisms employed on airplane seats and the like are in almost constant use and are usually cycled a number of times each day. As a consequence, the control mechanism associated with each seat is subject to frequent maintenance and adjustment checks. It is therefore, highly desirous that the push button control can be quickly and easily removed and reassembled with the hydraulic lock without the need of tools and the like thereby minimizing the amount of down time required for periodic maintenance.